A search for peculiar stars in the open cluster Hogg 16

• Published in: New astronomy Vol. 58; pp. 1 - 9
• Main Authors: Cariddi, Stefano, Azatyan, Naira M., Kurfürst, Petr, Štofanová, Lýdia, Netopil, Martin, Paunzen, Ernst, Pintado, Olga I., Aidelman, Yael J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2018
• Subjects: Open clusters and associations: individual (Hogg 16); Stars: chemically peculiar; Stars: emission-line; Techniques: photometric; Techniques: photometric; Be; Stars: chemically peculiar; Stars: emission-line; Open clusters and associations: individual (Hogg 16)
• ISSN: 1384-1076; 1384-1092
• DOI: 10.1016/j.newast.2017.07.002

•We present an analysis of the young open cluster Hogg 16.•Photometric and spectroscopic data were used for a detailed study.•We have estimated the fundamental cluster parameters.•The cluster metallicity was derived for the first time.•We identified and discuss several chemically peculiar cluster stars. The study of chemically peculiar (CP) stars in open clusters provides valuable information about their evolutionary status. Their detection can be performed using the Δa photometric system, which maps a characteristic flux depression at λ ∼ 5200 Å. This paper aims at studying the occurrence of CP stars in the earliest stages of evolution of a stellar population by applying this technique to Hogg 16, a very young Galactic open cluster ( ∼ 25 Myr). We identified several peculiar candidates: two B-type stars with a negative Δa index (CD - 60 4701, CPD - 60 4706) are likely emission-line (Be) stars, even though spectral measurements are necessary for a proper classification of the second one; a third object (CD - 60 4703), identified as a Be candidate in literature, appears to be a background B-type supergiant with no significant Δa index, which does not rule out the possibility that it is indeed peculiar as the normality line of Δa for supergiants has not been studied in detail yet. A fourth object (CD - 60 4699) appears to be a magnetic CP star of 8  M⊙, but obtained spectral data seem to rule out this hypothesis. Three more magnetic CP star candidates are found in the domain of early F-type stars. One is a probable nonmember and close to the border of significance, but the other two are probably pre-main sequence cluster objects. This is very promising, as it can lead to very strong constraints to the diffusion theory. Finally, we derived the fundamental parameters of Hogg 16 and provide for the first time an estimate of its metal content.